<!DOCTYPE html>

<html lang="zh-cn">

<head>
    <meta charset="utf-8">
    <title>PromiseTest</title>
    <meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
</head>

<body>
    <script>
        Promise.all([]).then(() => {
            alert('Hello!');
        });
    </script>
</body>

</html>